tests: a5_test: Print wrong buffer correctly on error

Before this patch, osmo_hexdump is called stacked in th esame printf
function. As a result, the first returned buffer is overwriten by the
second, which means the printed buffers will show as the same always.

Change-Id: I364328a59da31537c6c9b969e34edd360b685081
diff --git a/tests/a5/a5_test.c b/tests/a5/a5_test.c
index 6d7cc3c..69f1035 100644
--- a/tests/a5/a5_test.c
+++ b/tests/a5/a5_test.c
@@ -48,7 +48,9 @@
 	osmo_hexparse(block, res, len);
 	osmo_ubit2pbit(buf, out, 114);
 	if (0 != memcmp(buf, res, len)) {
-		printf("FAIL\nGOT: [%d] %s\nEXP: [%d] %s\n", k, osmo_hexdump_nospc(buf, len), k, osmo_hexdump_nospc(res, len));
+		printf("FAIL:\n");
+		printf("GOT: [%d] %s\n", k, osmo_hexdump_nospc(buf, len));
+		printf("EXP: [%d] %s\n", k, osmo_hexdump_nospc(res, len));
 		return false;
 	}
 	printf("OK\n");